Electrical signals are fundamental to key biological events such as brain activity, heartbeat, or vital hormone secretion. Their capture and analysis provide insight into cell or organ physiology and a number of bioelectronic medical devices aim to improve signal acquisition. Organic electrochemical transistors (OECT) have proven their capacity to capture neuronal and cardiac signals with high fidelity and amplification. Vertical PEDOT:PSS-based OECTs (vOECTs) further enhance signal amplification and device density but have not been characterized in biological applications. An electronic board with individually tuneable transistor biases overcomes fabrication induced heterogeneity in device metrics and allows quantitative biological experiments. Careful exploration of vOECT electric parameters defines voltage biases compatible with reliable transistor function in biological experiments and provides useful maximal transconductance values without influencing cellular signal generation or propagation. This permits successful application in monitoring micro-organs of prime importance in diabetes, the endocrine pancreatic islets, which are known for their far smaller signal amplitudes as compared to neurons or heart cells. Moreover, vOECTs capture their single-cell action potentials and multicellular slow potentials reflecting micro-organ organizations as well as their modulation by the physiological stimulator glucose. This opens the possibility to use OECTs in new biomedical fields well beyond their classical applications.

Spatiotemporal controlled drug delivery minimizes side-effects and enables therapies that require specific dosing patterns. Conjugated polymers (CP) can be used for electrically controlled drug delivery; however so far, most demonstrations were limited to molecules up to 500 Da. Larger molecules could be incorporated only during the CP polymerization and thus limited to a single delivery. This work harnesses the record volume changes of a glycolated polythiophene p(g3T2) for controlled drug delivery. p(g3T2) undergoes reversible volumetric changes of up to 300% during electrochemical doping, forming pores in the nm-size range, resulting in a conducting hydrogel. p(g3T2)-coated 3D carbon sponges enable controlled loading and release of molecules spanning molecular weights of 800-6000 Da, from simple dyes up to the hormone insulin. Molecules are loaded as a combination of electrostatic interactions with the charged polymer backbone and physical entrapment in the porous matrix. Smaller molecules leak out of the polymer while larger ones could not be loaded effectively. Finally, this work shows the temporally patterned release of molecules with molecular weight of 1300 Da and multiple reloading and release cycles without affecting the on/off ratio.

Electrochemical doping of organic mixed ionic-electronic conductors is key for modulating their conductivity, charge storage and volume enabling high performing bioelectronic devices such as recording and stimulating electrodes, transistors-based sensors and actuators. However, electrochemical doping has not been explored to the same extent for modulating the mechanical properties of OMIECs on demand. Here, we report a qualitative and quantitative study on how the mechanical properties of a glycolated polythiophene, p(g3T2), change in situ during electrochemical doping and de-doping. The Young's modulus of p(g3T2) changes from 69 MPa in the dry state to less than 10 MPa in the hydrated state and then further decreases down to 0.4 MPa when electrochemically doped. With electrochemical doping-dedoping the Young's modulus of p(g3T2) changes by more than one order of magnitude reversibly, representing the largest modulation reported for an OMIEC. Furthermore, we show that the electrolyte concentration affects the magnitude of the change, demonstrating that in less concentrated electrolytes more water is driven into the film due to osmosis and therefore the film becomes softer. Finally, we find that the oligo ethylene glycol side chain functionality, specifically the length and asymmetry, affects the extent of modulation. Our findings show that glycolated polythiophenes are promising materials for mechanical actuators with a tunable modulus similar to the range of biological tissues, thus opening a pathway for new mechanostimulation devices. This work investigates the changes in the mechanical properties of glycolated polythiophenes induced by electrochemical addressing and by electrolyte concentration, due to its ability to stabilize water.

During the last decades, tremendous efforts have been carried out to develop flexible electronics for a vast array of applications. Among all different applications investigated in this area, flexible displays have gained significant attention, being a vital part of large-area devices, portable systems and electronic labels etc electrophoretic (EP) ink displays have outstanding properties such as a superior optical switch contrast and low power consumption, besides being compatible with flexible electronics. However, the EP ink technology requires an active matrix-addressing scheme to enable exclusive addressing of individual pixels. EP ink pixels cannot be incorporated in low cost and easily manufactured passive matrix circuits due to the lack of threshold voltage and nonlinearity, necessities to provide addressability. Here, we suggest a simple method to introduce nonlinearity and threshold voltage in EP ink display cells in order to make them passively addressable. Our method exploits the nonlinearity of an organic ferroelectric capacitor that introduces passive addressability in display cells. The organic ferroelectric material poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) is here chosen because of its simple manufacturing protocol and good polarizability. We demonstrate that a nonlinear EP cell with bistable states can be produced by depositing a P(VDF-TrFE) film on the bottom electrode of the display cell. The P(VDF-TrFE) capacitor and the EP ink cell are separately characterized in order to match the surface charge at their respective interfaces and to achieve and optimize bistable operation of display pixels.

H2O2 plays a significant role in a range of physiological processes where it performs vital tasks in redox signaling. The sensitivity of many biological pathways to H2O2 opens up a unique direction in the development of bioelectronics devices to control levels of reactive-oxygen species (ROS). Here a microfabricated ROS modulation device that relies on controlled faradaic reactions is presented. A concentric pixel arrangement of a peroxide-evolving cathode surrounded by an anode ring which decomposes the peroxide, resulting in localized peroxide delivery is reported. The conducting polymer (poly(3,4-ethylenedioxythiophene) (PEDOT), is exploited as the cathode. PEDOT selectively catalyzes the oxygen reduction reaction resulting in the production of hydrogen peroxide (H2O2). Using electrochemical and optical assays, combined with modeling, the performance of the devices is benchmarked. The concentric pixels generate tunable gradients of peroxide and oxygen concentrations. The faradaic devices are prototyped by modulating human H2O2-sensitive Kv7.2/7.3 (M-type) channels expressed in a single-cell model (Xenopus laevis oocytes). The Kv7 ion channel family is responsible for regulating neuronal excitability in the heart, brain, and smooth muscles, making it an ideal platform for faradaic ROS stimulation. The results demonstrate the potential of PEDOT to act as an H2O2 delivery system, paving the way to ROS-based organic bioelectronics.

In the search for understanding and communicating with all biological systems, in humans, animals, plants, and even microorganisms, we find a common language of all communicating via electrons, ions and molecules. Since the discovery of organic electronics, the ability to bridge the gap and communicate be-tween modern technology and biology has emerged. Organic chemistry pro-vides us with tools for understanding and a material platform of polymer electronics for communication. Such insights give us not only the ability to observe fundamental phenomenon but to actively design and construct materials with chemical functionalities towards better interfaces and applications. Organic electronic materials and devices have found their way to be implemented in the field of medicine for diagnostic and therapeutic purposes, but also in water purification and to help tackle the monumental task in creating the next generation of sustainable energy production and storage. Ultimately it’s safe to say that organic electronics are not going to replace our traditional technology based on inorganic materials but rather the two fields can find a way to complement each other for various purposes and applications. Compared to conventional silicon based technology, production of carbon-based organic electronic polymer materials are extremely cheap and devices can even be made flexible and soft with great compatibility towards biology.  

The main focus of this thesis has been developing and synthesizing new types of organic electronic and ionic conductive polymeric materials. Rational chemical design and modifications of the materials have been utilized to introduce specific functionalities to the materials. The functionalities serving the purpose to facilitate ion and electron conductive charge transport for organic electronics and with biological interface implementation of the polymer materials. 

Multi-functional ionic conductive hyperbranched polyglycerol polyelectrolytes (dendrolytes) were developed comprising both ionically charged groups and cross-linkable groups. The hyperbranched polyglycerol core structure of the material possesses a hydrophilic solvating platform for both ions and maintenance of solvent molecules, while being a biocompatible structure. Coupled with the peripheral charged ionic functionalities of the polymer, the dendrolyte materials are highly ionic conductive and selective towards cationic and anionic charged atoms and large molecules when implemented as ion-exchange membranes. Homogenous ion-exchange membrane casting has been achieved by the implementation of cross-linkable functionalities in the dendrolytes, utilizing robust click-chemistry for efficient micro and macro fabrication processing of the ion-ex-change membranes for organic electronic devices. The ion-exchange membrane material was implemented in electrophoretic drug delivery devices (organic electronic ion pumps), which are used for delivery of ions and neurotransmitters with spatiotemporal resolution and are able to communicate and be used for therapeutic drug delivery purposes in biological interfaces. The dendrolyte materials were also able to form free-standing membranes, making it possible for implementation in fuel cell and desalination purposes. 

Trimeric conjugated thiophene pre-polymer structures were also developed in the thesis and synthesized for the purpose of implementation of the material in vivo to form electrically conductive polymer structures, and in such manner to be able to create electrodes and ultimately to connect with the central nervous system. The conjugated pre-polymers being both water soluble and enzymatically polymerizable serve as a platform to realize such a concept. Also, modifying the trimeric structure with cross-linkable functionality created the capability to form better interfaces and stability towards biological environments.   

In the emerging field of organic bioelectronics, conducting polymers and ion-selective membranes are combined to form resistors, diodes, transistors, and circuits that transport and process both electronic and ionic signals. Such bioelectronics concepts have been explored in delivery devices that translate electronic addressing signals into the transport and dispensing of small charged biomolecules at high specificity and spatiotemporal resolution. Manufacturing such "iontronic" devices generally involves classical thin film processing of polyelectrolyte layers and insulators followed by application of electrolytes. This approach makes miniaturization and integration difficult, simply because the ion selective polyelectrolytes swell after completing the manufacturing. To advance such bioelectronics/iontronics and to enable applications where relatively larger molecules can be delivered, it is important to develop a versatile material system in which the charge/size selectivity can be easily tailormade at the same time enabling easy manufacturing of complex and miniaturized structures. Here, we report a one-pot synthesis approach with minimal amount of organic solvent to achieve cationic hyperbranched polyglycerol films for iontronics applications. The hyperbranched structure allows for tunable pre multi-functionalization, which combines available unsaturated groups used in crosslinking along with ionic groups for electrolytic properties, to achieve a one-step process when applied in devices for monolithic membrane gel formation with selective electrophoretic transport of molecules.

Polymer-based ion exchange membranes (IEMs) are utilized for many applications such as in water desalination, energy storage, fuel cells and in electrophoretic drug delivery devices, exemplified by the organic electronic ion pump (OEIP). The bulk of current research is primarily focused on finding highly conductive and stable IEM materials. Even though great progress has been made, a lack of fundamental understanding of how specific polymer properties affect ionic transport capabilities still remains. This leads to uncertainty in how to proceed with synthetic approaches for designing better IEM materials. In this study, an investigation of the structure-property relationship between polymer size and ionic conductivity was performed by comparing a series of membranes, based on ionically charged hyperbranched polyglycerol of different polymer sizes. Observing an increase in ionic conductivity associated with increasing polymer size and greater electrolyte exclusion, indi-cating an ionic transportation phenomenon not exclusively based on membrane electrolyte uptake. These findings further our understanding of ion transport phenomena in semi-permeable membranes and indicate a strong starting point for future design and synthesis of IEM polymers to achieve broader capabilities for a variety of ion transport-based applications.

Doped semiconductors nanostructures (NSs) have shown great interest as a potential for green and efficient photocatalysis activities. Magnesium (Mg)-doped zinc oxide (ZnO) nanoparticles (NPs) has been synthesized by a one-step chemical low temperature (60 °C) co-precipitation method without further calcination and their photocatalytic performance for photodegradation of Methylene blue (MB) dye under the illumination of solar light is investigated. The crystal structure of the synthesized NPs is examined by X-ray diffraction (XRD). XRD data indicates a slight shift towards higher 2θ angle in Mg-doped samples as compared to the pure ZnO NPs which suggest the incorporation of Mg2+ into ZnO crystal lattice. X-ray photoelectron spectroscopy (XPS), UV–Vis spectrophotometer and cathodoluminescence (CL) spectroscopy, were used to study electronics, and optical properties, respectively. The XPS analysis confirms the substitution of the Zn2+ by the Mg2+ into the ZnO crystal lattice in agreement with the XRD data. The photocatalytic activities showed a significant enhancement of the Mg-doped ZnO NPs in comparison with pure ZnO NPs. Hole/radical scavengers were used to reveal the mechanism of the photodegradation. It was found that the addition of the Mg to the ZnO lattices increases the absorption of the hydroxyl ions at the surface of the NPs and hence acts as a trap site leading to decrease the electron-hole pair and consequently enhancing the photodegradation.

Albeit tris(8-hydroxyquinolinato) aluminum (Alq(3)) and its derivatives are prominent emitter materials for organic lighting devices, and the optical transitions occur among ligand-centered states, the use of metal-free 8-hydroxyquinoline is impractical as it suffers from strong nonradiative quenching, mainly through fast proton transfer. Herein, it is shown that the problem of rapid proton exchange and vibration quenching of light emission can be overcome not only by complexation, but also by organization of the 8-hydroxyquinolinium cations into a solid rigid network with appropriate counter-anions (here bis(trifluoromethanesulfonyl)imide). The resulting structure is stiffened by secondary bonding interactions such as pi-stacking and hydrogen bonds, which efficiently block rapid proton transfer quenching and reduce vibrational deactivation. Additionally, the optical properties are tuned through methyl substitution from deep blue (455 nm) to blue-green (488 nm). Time-dependent density functional theory (TDFT) calculations reveal the emission to occur from which an unexpectedly long-lived S-1 level, unusual for organic fluorophores. All compounds show comparable, even superior photoluminescence compared to Alq(3) and related materials, both as solids and thin films with quantum yields (QYs) up to 40-50%. In addition, all compounds show appreciable thermal stability with decomposition temperatures above 310 degrees C.

Producing thick films of conducting polymers by a low-cost manufacturing technique would enable new applications. However, removing huge solvent volume from diluted suspension or dispersion (1-3 wt%) in which conducting polymers are typically obtained is a true manufacturing challenge. In this work, a procedure is proposed to quickly remove water from the conducting polymer poly(3,4-ethylenedioxythiophene:poly(4-styrene sulfonate) (PEDOT:PSS) suspension. The PEDOT:PSS suspension is first flocculated with 1 m H2SO4 transforming PEDOT nanoparticles (approximate to 50-500 nm) into soft microparticles. A filtration process inspired by pulp dewatering in a paper machine on a wire mesh with apertures dimension between 60 mu m and 0.5 mm leads to thick free-standing films (approximate to 0.5 mm). Wire mesh clogging that hinders dewatering (known as dead-end filtration) is overcome by adding to the flocculated PEDOT: PSS dispersion carbon fibers that aggregate and form efficient water channels. Moreover, this enables fast formation of thick layers under simple atmospheric pressure filtration, thus making the process truly scalable. Thick freestanding PEDOT films thus obtained are used as electrocatalysts for efficient reduction of oxygen to hydrogen peroxide, a promising green chemical and fuel. The inhomogeneity of the films does not affect their electrochemical function.

Lignin, obtained as a waste product in huge quantities from the large-scale cellulose processing industries, holds a great potential to be used as sustainable electrode material for large-scale electroactive energy storage systems. The fixed number of redox-active phenolic groups present within the lignin structure limits the electrochemical performance and the total energy storage capacity of the lignin-based electrodes. Herein, the way to enhance the charge storage capacity of lignin by incorporating additional small catechol molecules into the lignin structure is demonstrated. The catechol derivatives are covalently attached to the lignin via aromatic electrophilic substitution reaction. The increased phenolic groups in all functionalized lignin derivatives notably increase the values of capacitance compared to pristine lignin. Further, solvent fractionation of lignin followed by functionalization using catechol boosts three times the charge capacity of lignin electrode. Herein, a scalable, cost-effective method to enhance the electrochemical performance of lignin electrodes via incorporation of small redox active moieties into the lignin structure is demonstrated. Solvent fractionation of lignin followed by functionalization using catechol increases the charge storage capacity of the lignin-carbon composite electrode by a factor of 3 reaching record high charge capacity above 100 mAh g-1.

The safety risks associated with organic solvent-based batteries for stationary energy storage have driven scientists to reconsider aqueous electrolytes combined with ultra low-cost materials. In this context, zinc (Zn) metal and biopolymer lignin are certainly among the most abundant and economical electroactive materials on Earth, displaying compatibility in their redox activity to fit the stability window of aqueous electrolytes. But, up to now, the electrolyte solutions in those systems incorporate fluorinated organic salts or bio-ionic liquids, both of which are detrimental to the environment and expensive. In this work we use a state-of-the-art lignin electrode based on catechol functionalized lignin (LC) nano-composited with carbon black (C) and a biopolymer hydrogel electrolyte based on agarose with non-fluorinated Zn salt. The optimization of the hydrogel's composition was realized by reducing the amount of free water by promoting its bonding with additional glycerol. The hydrogel facilitates the growth of Zn in the (002) plane, preventing dendritic formation. The highest discharge capacity of 79.7 mA h gLC-1 was obtained at 0.05 A g-1 charge/discharge rate for the buffered 3% agarose hydrogel electrolyte containing 25% glycerol with 1 M Zn2+. The hydrogel containing 25% glycerol with 1 M Zn2+ and 1 M K+ in the absence of buffering shows the best cycle performance with 78% capacity retention after 26 000 cycles at 1 A g-1 with a capacity of 58 mA h gLC-1 at 0.05 A g-1. This study shows the possibility of a safe, affordable, bio-based environmentally friendly energy storage system that has the potential for large-scale applications.

Lignin, a byproduct from the pulp industry, is one of the redox active biopolymers being investigated as a component in the electrodes for sustainable energy storage applications. Due to its insulating nature, it needs to be combined with a conductor such as carbon or conducting polymer for efficient charge storage. Here, the lignin/carbon composite electrodes manufactured via mechanical milling (ball milling) are reported. The composite formation, correlation between performance and morphology is studied by comparison with manual mixing and jet milling. Superior charge storage capacity with approximate to 70% of the total contribution from the Faradaic process involving the redox functionality of lignin is observed in a mechanically milled composite. In comparison, manual mix shows only approximate to 30% from the lignin storage participation while the rest is due to the electric double layer at the carbon-electrolyte interface. The significant participation of lignin in the ball milled composite is attributed to the homogeneous, intimate mixing of the carbon and the lignin leading the electronic carrier transported in the carbon phase to reach most of the redox group of lignin. A maximum capacity of 49 mAh g(-1) is obtained at charge/discharge rate of 0.25 A g(-1) for the sample milled for 60 min.

The key figure-of-merit for materials in stationary energy storage applications, such as large-scale energy storage for buildings and grids, is the cost per kilo per electrochemical cycle, rather than the energy density. In this regard, forest-based biopolymers such as lignin, are attractive, as they are abundant on Earth. Here, we explored lignin as an electroactive battery material, able to store two electrons per hydroquinone aromatic ring, with the targeted operation in aqueous electrolytes. The impact of the sulfonation level of lignin on the performance of its composite electrode with carbon was investigated by considering three lignin derivatives: lignosulfonate (LS), partially desulfonated lignosulfonate (DSLS), and fully desulfonated lignin (KL, lignin produced by the kraft process). Partial desulfonation helped in better stability of the composite in aqueous media, simultaneously favoring its water processability. In this way, a route to promote ionic conductivity within the lignin/carbon composite electrodes was developed, facilitating the access to the entire bulk of the volumetric electrodes. Electrochemical performance of DSLS/C showed highly dominant Faradaic contribution (66%) towards the total capacity, indicating an efficient mixed ionic-electronic transport within the lignin-carbon phase, displaying a capacity of 38 mAh/g at 0.25 A/g and 69% of capacity retention after 2200 cycles at a rate of 1 A/g.

For their pungency and tanginess, ginger rhizomes (Zingiber officinale) are often used in cooking. Ginger has long been used in traditional medicine and home remedies to treat pain and inflammation. This research tests Z. officinale (EOZ) essential oils' chemical composition, insecticidal, and antioxidant properties in vitro and in silico. EOZ yielded 0.69% of root mass with 23 chemicals. The main chemicals in EOZ were alpha-zingiberene (23.850%), Geranial (14.160%), and (E,E)-alpha-farnesene (9.980%). EOZ demonstrated noteworthy antioxidant activity in all tests, with an IC50 of 9.53 +/- 0.41 mg/mL in the DPPH test and an EC50 of 87.46 +/- 3.19 mg/mL in the FRAP system. The results indicate that EOZ has strong efficacy against C. maculatus, even at low concentrations (1.00 mu L/100 g). Note that EOZ killed 20 +/- 0% and 13.33 +/- 4.44% of adult C. maculatus in inhalation and contact tests, respectively. High concentration (20.00 mu L/100 g) resulted in 100% adult mortality in inhalation tests and 96.67 +/- 4.44% mortality in contact testing. We then used molecular docking to identify EO major component binding modes by targeting insecticidal and antioxidant protein structures 1R20 and 1R4U. This research helps create insecticides and antioxidants from common ginger essential oil.

We demonstrate the fabrication, by exclusive means of inkjet-printing, of capacitive relative humidity sensors on flexible, plastic substrate. These sensors can be successfully used for the measurement of relative-humidity in both air and common soil. We also show that the same technique may be used for the fabrication of the same type of sensors on the surface of the leaves of El AE gnus Ebbingei (silverberry).Our results demonstrate the suitability of leaves as substrate for printed electronics and pave the way to the next generation of sensors to be used in fields such as agriculture and flower farming.

The mass implementation of renewable energies is limited by the absence of efficient and affordable technology to store electrical energy. Thus, the development of new materials is needed to improve the performance of actual devices such as batteries or supercapacitors. Herein, the facile consecutive chemically oxidative polymerization of poly(1-amino-5-chloroanthraquinone) (PACA) and poly(3,4-ethylenedioxythiophene (PEDOT) resulting in a water dispersible material PACA-PEDOT is shown. The water-based slurry made of PACA-PEDOT nanoparticles can be processed as film coated in ambient atmosphere, a critical feature for scaling up the electrode manufacturing. The novel redox polymer electrode is a nanocomposite that withstands rapid charging (16 A g−1) and delivers high power (5000 W kg−1). At lower current density its storage capacity is high (198 mAh g−1) and displays improved cycling stability (60% after 5000 cycles). Its great electrochemical performance results from the combination of the redox reversibility of the quinone groups in PACA that allows a high amount of charge storage via Faradaic reactions and the high electronic conductivity of PEDOT to access to the redox-active sites. These promising results demonstrate the potential of PACA-PEDOT to make easily organic electrodes from a water-coating process, without toxic metals, and operating in non-flammable aqueous electrolyte for large scale pseudocapacitors. 

The development of energy storage devices with higher energy and power outputs, and long cycling stability is urgently required in the pursuit of the expanding challenges of electrical energy storage. The utilization of biologically renewable redox compounds holds a great potential in designing sustainable energy storage systems and contributes in reducing the dependence on fossil fuels for energy materials. Quinones are the principal redox centers in natural organic materials and play a key role as charge storage electrode materials because of their abundance, multiple forms and integration into the materials flow through the biosphere. Electrical energy storage devices and systems can be significantly improved by the combination of scalable quinone-based biomaterials with good electronic conductors. This review uses recent examples to show how biopolymers are providing new directions in the development of renewable biohybrid electrodes for energy storage devices.

A trihybrid bioelectrode composed of lignin, poly(3,4-ethylenedioxythiophene) (PEDOT), and poly(aminoanthraquinone) (PAAQ) is prepared by a two-step galvanostatic electropolymerization, and characterized for supercapacitor applications. Using PEDOT/Lignin as a base layer, followed by the consecutive deposition of PAAQ, the hybrid electrode PEDOT/Lignin/PAAQ shows a high specific capacitance of 418 F g(-1) with small self-discharge. This trihybrid electrode material can be assembled into symmetric and asymmetric super-capacitors. The asymmetric supercapacitor uses PEDOT + Lignin/PAAQ as positive electrode and PEDOT/PAAQ as negative electrode, and exhibits superior electrochemical performance due to the synergistic effect of the two electrodes, which leads to a specific capacitance of 74 F g(-1). It can be reversibly cycled in the voltage range of 0-0.7 V. More than 80% capacitance is retained after 10 000 cycles. These remarkable features reveal the exciting potential of a full organic energy storage device with long cycle life.

Polyvinylidene difluoride (PVDF) derivatives in metal/PVDF/metal (MPM) sandwich structures have been studied extensively since 1969. Cousin copolymers of the same family have been discovered with fascinating piezoelectric, pyroelectric, electrocaloric, and ferroelectric properties. Solution processing, flexibility, lightweight, and thermal stability make this class of materials complementary to inorganics. Thus, PVDF based polymers potentially compete with inorganic materials for a broad range of technologies such as energy generators, loudspeakers, coolers, and memories. However, the stable non-electroactive α-phase and hydrophobic nature of PVDF are the main barriers for developoing high performing and robust MPM devices in electronic applications. In this review, we present an up-to-date overview on different methods to induce the electroactive β-phase and improve the adhesion strength with metals to ensure robust and durable MPM devices. We go through advantages and disadvantages of several methods and pinpoint future opportunities in this research area. A special attention is paid to wearable piezoelectric nanogenerators for energy harvesting from human body motion, where flexible PVDF derivatives are compared with rigid piezoelectric ceramics. While the piezoelectric coefficient of PVDF (d₃₃ ~ 24–34 pm/V) is one order lower than ceramic materials, novel co-polymers of PVDF display d₃₃ > 1000 pm/V upon bias. This shows promise to bring piezoelectrics to flexible and large-area applications such as smart textiles. We also discussed challenges to improve wearability, such as light weight, breathability, and flexibility.

In this study, density functional theory (DFT) combined with time-dependent (TD) DFT calculations were employed to investigate the photoisomerization reaction kinetics of two near infrared (NIR) heptamethine cyanine (Cy7-NH3 and Cy7-SO3) dyes in the ground singlet state and the first excited singlet state. We found that the photoisomerization of the ground state all- trans Cy7 molecules results in at least one mono- cis and one all- cis species that demonstrate redshifted emission, in agreement with recently published transient state excitation modulation spectroscopy and fluorescence correlation spectroscopy measurements. The transition states were estimated for a whole photoisomerization pathway for both the ground singlet and first excited singlet state potential energy surfaces. We have found that all- cis isomers of the studied Cy7 dyes can be achieved through a sequential two-step photoisomerization within the excited singlet state potential energy surface, along the double CC bond adjacent to edge group (leading to mono- cis isomer 1) and along the double CC bond adjacent to the central-chain group (leading to mono- cis isomer 2). Computations show that all-trans -> trans -> mono- cis isomer 1 -> all-cis -> all- cis kinetics is limited by the first trans -> -> mono- cis isomer 1 stage, while the all-trans -> trans -> mono- cis isomer 2 -> all-cis -> all- cis pathway is limited by the second mono- cis isomer 2 -> all-cis -> all- cis stage. . Accounting for the fact that mono- cis isomer 2 demonstrates red-shifted emission compared to the all-trans form and that this mono- cis isomer 2 is reachable through the energetically favorable all-trans -> trans -> mono- cis isomer 2 stage, we concluded that the experimentally observed red-shifted emission by Cy7-NH3 and Cy7-SO3 should be assigned to the formation of mono- cis isomer 2 species. If the all- cis isomer is populated through the double-step photoisomerization it can also be considered as a source of red-shifted emission. However, as follows from our simulations, the all- cis isomer is kinetically intricate to achieve compared to the mono- cis isomer 2.

Polymer solar cells using non-fullerene acceptors are nowadays amongst the most promising approaches for next generation photovoltaic applications. However, there are still remaining challenges related to large-scale fully solution-processing of high efficiency solar cells as high efficiencies are obtained only for very small areas using hole transport layers based on evaporated molybdenum oxide. Solution-processable hole transport materials compatible with non-fullerene acceptor materials are still scarce and thus considered as one of the major challenges nowadays. In this work, we present copper-doped nickel oxide nanocrystals that form highly stable inks in alcohol-based solutions. This allows processing of efficient hole transport layers in both regular and inverted device structures of polymer solar cells. As the initial work function of these ionic doped materials is too low for efficient hole extraction, doping the nanocrystals with an organic electron acceptor, namely 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquino dimethane (F4-TCNQ), was additionally applied to make the work function more suitable for hole extraction. The resulting hybrid hole transport layers were first studied in polymer solar cells based on fullerene acceptors using regular device structures yielding 7.4% efficiency identical to that of reference cells based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). For inverted device structures, the hybrid hole transport layers were processed on top of blends based on the non-fullerene acceptor IT-4F and PBDB-T-2F donor. The corresponding solar cells showed promising efficiencies up to 7.9% while the reference devices using PEDOT:PSS showed inferior performances. We further show that the hybrid hole transport layer can be used to tune the color of the polymer solar cells using optical spacer effects.

N-type semiconducting polymers have been recently utilized in thermoelectric devices, however they have typically exhibited low electrical conductivities and poor device stability, in contrast to p-type semiconductors, which have been much higher performing. This is due in particular to the n-type semiconductors low doping efficiency, and poor charge carrier mobility. Strategies to enhance the thermoelectric performance of n-type materials include optimizing the electron affinity (EA) with respect to the dopant to improve the doping process and increasing the charge carrier mobility through enhanced molecular packing. Here, we report the design, synthesis and characterization of fused electron-deficient n-type copolymers incorporating the electron withdrawing lactone unit along the backbone. The polymers were synthesized using metal-free aldol condensation conditions to explore the effect of enlarging the central phenyl ring to a naphthalene ring, on the electrical conductivity. When n-doped with N-DMBI, electrical conductivities of up to 0.28 S cm(-1), Seebeck coefficients of -75 mu V K-1 and maximum Power factors of 0.16 mu W m(-1) K-2 were observed from the polymer with the largest electron affinity of -4.68 eV. Extending the aromatic ring reduced the electron affinity, due to reducing the density of electron withdrawing groups and subsequently the electrical conductivity reduced by almost two orders of magnitude.

Three lactone-based rigid semiconducting polymers were designed to overcome major limitations in the development of n-type organic thermoelectrics, namely electrical conductivity and air stability. Experimental and theoretical investigations demonstrated that increasing the lactone group density by increasing the benzene content from 0 % benzene (P-0), to 50 % (P-50), and 75 % (P-75) resulted in progressively larger electron affinities (up to 4.37 eV), suggesting a more favorable doping process, when employing (N-DMBI) as the dopant. Larger polaron delocalization was also evident, due to the more planarized conformation, which is proposed to lead to a lower hopping energy barrier. As a consequence, the electrical conductivity increased by three orders of magnitude, to achieve values of up to 12 S cm and Power factors of 13.2 mu Wm(-1) K-2 were thereby enabled. These findings present new insights into material design guidelines for the future development of air stable n-type organic thermoelectrics.

The quest for eco-friendly materials with anticipated positive impact for sustainability is crucial to achieve the UN sustainable development goals. Classical strategies of composite materials can be applied on novel nanomaterials and green materials. Besides the actual technology and applications also processing and manufacturing methods should be further advanced to make entire technology concepts sustainable. Here, they show an efficient way to combine two low-cost materials, cellulose and zinc oxide (ZnO), to achieve novel functional and "green" materials via paper-making processes. While cellulose is the most abundant and cost-effective organic material extractable from nature. ZnO is cheap and known of its photocatalytic, antibacterial, and UV absorption properties. ZnO nanowires are grown directly onto cellulose fibers in water solutions and then dewatered in a process mimicking existing steps of large-scale papermaking technology. The ZnO NW paper exhibits excellent photo-conducting properties under simulated sunlight with good ON/OFF switching and long-term stability (90 minutes). It also acts as an efficient photocatalyst for hydrogen peroxide (H2O2) generation (5.7 x 10(-9) m s(-1)) with an envision the possibility of using it in buildings to enable large surfaces to spontaneously produce H2O2 at its outer surface. Such technology promise for fast degradation of microorganisms to suppress the spreading of diseases.

We investigate the gas-phase structure of the neutral pentaalanine peptide. The IR spectrum in the 340-1820 cm-1 frequency range is obtained by employing supersonic jet cooling, infrared multiphoton dissociation, and vacuum-ultraviolet action spectroscopy. Comparison with quantum chemical spectral calculations suggests that the molecule assumes multiple stable conformations, mainly of two structure types. In the most stable conformation theoretically found, the N-terminus forms a C5 ring and the backbone resembles that of an 310-helix with two beta-turns. Additionally, the conformational preferences of pentaalanine have been evaluated using Born-Oppenheimer molecular dynamics, showing that a nonzero simulation time step causes a systematic frequency shift.

The communication outposts of the emerging Internet of Things are embodied by ordinary items, which desirably include all-printed flexible sensors, actuators, displays and akin organic electronic interface devices in combination with silicon-based digital signal processing and communication technologies. However, hybrid integration of smart electronic labels is partly hampered due to a lack of technology that (de)multiplex signals between silicon chips and printed electronic devices. Here, we report all-printed 4-to-7 decoders and seven-bit shift registers, including over 100 organic electrochemical transistors each, thus minimizing the number of terminals required to drive monolithically integrated all-printed electrochromic displays. These relatively advanced circuits are enabled by a reduction of the transistor footprint, an effort which includes several further developments of materials and screen printing processes. Our findings demonstrate that digital circuits based on organic electrochemical transistors (OECTs) provide a unique bridge between all-printed organic electronics (OEs) and low-cost silicon chip technology for Internet of Things applications.

Vertical organic electrochemical transistors (OECTs) have been manufactured solely using screen printing. The OECTs are based on PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly (styrene sulfonic acid)), which defines the active material for both the transistor channel and the gate electrode. The resulting vertical OECT devices and circuits exhibit low-voltage operation, relatively fast switching, small footprint and high manufacturing yield; the last three parameters are explained by the reliance of the transistor configuration on a robust structure in which the electrolyte vertically bridges the bottom channel and the top gate electrode. Two different architectures of the vertical OECT have been manufactured, characterized and evaluated in parallel throughout this report. In addition to the experimental work, SPICE models enabling simulations of standalone OECTs and OECT-based circuits have been developed. Our findings may pave the way for fully integrated, low-voltage operating and printed signal processing systems integrated with e.g. printed batteries, solar cells, sensors and communication interfaces. Such technology can then serve a low-cost base technology for the internet of things, smart packaging and home diagnostics applications.

Here, we report all-screen printed display driver circuits, based on organic electrochemical transistors (OECTs), and their monolithic integration with organic electrochromic displays (OECDs). Both OECTs and OECDs operate at low voltages and have similar device architectures, and, notably, they rely on the very same electroactive material as well as on the same electrochemical switching mechanism. This then allows us to manufacture OECT-OECD circuits in a concurrent manufacturing process entirely based on screen printing methods. By taking advantage of the high current throughput capability of OECTs, we further demonstrate their ability to control the light emission in traditional light-emitting diodes (LEDs), where the actual LED addressing is achieved by an OECT-based decoder circuit. The possibility to monolithically integrate all-screen printed OECTs and OECDs on flexible plastic foils paves the way for distributed smart sensor labels and similar Internet of Things applications. 

Cellulose nanocrystals (CNCs) possess the ability to form helical periodic structures that generate structural colors. Due to the helicity, such self-assembled cellulose structures preferentially reflect left-handed circularly polarized light of certain colors, while they remain transparent to right-handed circularly polarized light. This study shows that combination with a liquid crystal enables modulation of the optical response to obtain light reflection of both handedness but with reversed spectral profiles. As a result, the nanophotonic systems provide vibrant structural colors that are tunable via the incident light polarization. The results are attributed to the liquid crystal aligning on the CNC/glucose film, to form a birefringent layer that twists the incident light polarization before interaction with the chiral cellulose nanocomposite. Using a photoresponsive liquid crystal, this effect can further be turned off by exposure to UV light, which switches the nematic liquid crystal into a nonbirefringent isotropic phase. The study highlights the potential of hybrid cellulose systems to create self-assembled yet advanced photoresponsive and polarization-tunable nanophotonics.

Photonic films based on cellulose nanocrystals (CNCs) are sustainable candidates for sensors, structurally colored radiative cooling, and iridescent coatings. Such CNC-based films possess a helicoidal nanoarchitecture, which gives selective reflection with the polarization of the incident light. However, due to the hygroscopic nature of CNCs, the structural colored material changes and may be irreversibly damaged at high relative humidity. Thus, moisture protection is essential in such settings. In this work, hygroscopic CNC-based films are protected with a bioinspired synthetic plant cuticle; a strategy already adopted by real plants. The protective cuticle layers altered the reflected colors to some extent, but more importantly, they significantly reduced the water vapor permeance by more than two orders of magnitude, from 2.1 x 10(7) (pristine CNC/GLU film) to 12.3 x 10(4) g mu m m(-2) day(-1) atm(-1) (protected CNC/GLU film). This expands significantly the time window of operation for CNC/GLU films at high relative humidity.

Cellulose nanomaterial (CNM)-based foams and aerogels with thermal conductivities substantially below the value for air attract significant interest as super-insulating materials in energy-efficient green buildings. However, the moisture dependence of the thermal conductivity of hygroscopic CNM-based materials is poorly understood, and the importance of phonon scattering in nanofibrillar foams remains unexplored. Here, we show that the thermal conductivity perpendicular to the aligned nanofibrils in super-insulating icetemplated nanocellulose foams is lower for thinner fibrils and depends strongly on relative humidity (RH), with the lowest thermal conductivity (14 mW m(-1) K-1) attained at 35% RH. Molecular simulations show that the thermal boundary conductance is reduced by the moisture-uptake-controlled increase of the fibril-fibril separation distance and increased by the replacement of air with water in the foam walls. Controlling the heat transport of hygroscopic super-insulating nanofibrillar foams by moisture uptake and release is of potential interest in packaging and building applications.

The signaling dynamics in neuronal networks includes processes ranging from lifelong neuromodulation to direct synaptic neurotransmission. In chemical synapses, the time delay it takes to pass a signal from one neuron to the next lasts for less than a millisecond. At the post-synaptic neuron, further signaling is either up- or down-regulated, dependent on the specific neurotransmitter and receptor. While this up- and down-regulation of signals usually runs perfectly well and enables complex performance, even a minor dysfunction of this signaling system can cause major complications, in the shape of neurological disorders. The field of organic bioelectronics has the ability to interface neurons with high spatiotemporal recording and stimulation techniques. Local chemical stimulation, i.e. local release of neurotransmitters, enables the possibility of artificially altering the chemical environment in dysfunctional signaling pathways to regain or restore neural function. To successfully interface the biological nervous system with electronics, a range of demands must be met. Organic bioelectronic techniques and materials are capable of reaching the demands on the biological as well as the electronic side of the interface. These demands span from high performance biocompatible materials, to miniaturized and specific device architectures, and high dose control on demand within milliseconds.

The content of this thesis is a continuation of the development of organic bioelectronic devices for neurotransmitter delivery. Organic materials are utilized to electrically control the dose of charged neurotransmitters by translating electric charge into controlled artificial release. The first part of the thesis, Papers 1 and 2, includes further development of the resistor-type release device called the organic electronic ion pump. This part includes material evaluation, microfluidic incorporation, and device design considerations. The aim for the second part of this thesis, Papers 3 and 4, is to enhance temporal performance, i.e. reduce the delay between electrical signal and neurotransmitter delivery to corresponding delay in biological neural signaling, while retaining tight dosage control. Diffusion of neurotransmitters between nerve cells is a slow process, but since it is restricted to short distances, the total time delay is short. In our organic bioelectronic devices, several orders of magnitude in speed can be gained by switching from lateral to vertical delivery geometries. This is realized by two different types of vertical diodes combined with a lateral preload and waste configuration. The vertical diode assembly was further expanded with a control electrode that enables individual addressing in each of several combined release sites. These integrated circuits allow for release of neurotransmitters with high on/off release ratios, approaching delivery times on par with biological neurotransmission.

Highly controlled drug delivery devices play an increasingly important role in the development of new neuroengineering tools. Stringent - and sometimes contradicting - demands are placed on such devices, ranging from robustness in freestanding devices, to overall device miniaturization, while maintaining precise spatiotemporal control of delivery with high chemical specificity and high on/off ratio. Here, design principles of a hybrid microfluidic iontronic probe that uses flow for long-range pressure-driven transport in combination with an iontronic tip that provides electronically fine-tuned pressure-free delivery are explored. Employing a computational model, the effects of decoupling the drug reservoir by exchanging a large passive reservoir with a smaller microfluidic system are reported. The transition at the microfluidic-iontronic interface is found to require an expanded ion exchange membrane inlet in combination with a constant fluidic flow, to allow a broad range of device operation, including low source concentrations and high delivery currents. Complementary to these findings, the free-standing hybrid probe monitored in real time by an external sensor is demonstrated. From these computational and experimental results, key design principles for iontronic devices are outlined that seek to use the efficient transport enabled by microfluidics, and further, key observations of hybrid microfluidic iontronic probes are explained.

Current neural interfaces rely on electrical stimulation pulses to affect neural tissue. The development of a chemical delivery technology, which can stimulate neural tissue with the bodys own set of signaling molecules, would provide a new level of sophistication in neural interfaces. Such technology should ideally provide highly local chemical delivery points that operate at synaptic speed, something that is yet to be accomplished. Here, the development of a miniaturized ionic polarization diode that exhibits many of the desirable properties for a chemical neural interface technology is reported. The ionic diode shows proper diode rectification and the current switches from off to on in 50 mu s at physiologically relevant electrolyte concentrations. A device model is developed to explain the characteristics of the ionic diode in more detail. In combination with experimental data, the model predicts that the ionic polarization diode has a delivery delay of 5 ms to reach physiologically relevant neurotransmitter concentrations at subcellular spatial resolution. The model further predicts that delays of amp;lt;1 ms can be reached by further miniaturization of the diode geometry. Altogether, the results show that ionic polarization diodes are a promising building block for the next generation of chemical neural interfaces.

True random number generation is not thought to be possible using a classical approach but by instead exploiting quantum mechanics genuine randomness can be achieved. Here, the authors demonstrate a certified quantum random number generation using a metal-halide perovskite light emitting diode as a source of weak coherent polarisation states randomly producing an output of either 0 or 1. The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize the fields of optical communication and lighting devices, due to their simplicity of fabrication and outstanding optical properties. Here we demonstrate that PeLEDs can also be used in the field of quantum technologies by implementing a highly-secure quantum random number generator (QRNG). Modern QRNGs that certify their privacy are posed to replace classical random number generators in applications such as encryption and gambling, and therefore need to be cheap, fast and with integration capabilities. Using a compact metal-halide PeLED source, we generate random numbers, which are certified to be secure against an eavesdropper, following the quantum measurement-device-independent scenario. The obtained generation rate of more than 10 Mbit s(-1), which is already comparable to commercial devices, shows that PeLEDs can work as high-quality light sources for quantum information tasks, thus opening up future applications in quantum technologies.

In the field of cryptography, it is crucial that the random numbers used in key generation are not only genuinely random but also private, meaning that no other party than the legitimate user must have information about the numbers generated. Quantum random number generators can offer both properties - fundamentally random output, as well as the ability to implement generators that can certify the amount of private randomness generated, in order to remove some side-channel attacks. In this study we introduce perovskite technology as a resilient platform for photonics, where the resilience is owed to perovskite's ease of manufacturing. This has the potential to mitigate disruptions in the supply chain by enabling local and domestic manufacturing of photonic devices. We demonstrate the feasibility of the platform by implementing a measurement-device independent quantum random number generator based on perovskite LEDs.

The construction of visible-light-driven hybrid heterostructure photocatalysts is of great significance for environmental remediation, although the utilization of strong visible-light response photocatalysts with high efficiency and stability remains a major challenge. Defect engineering is an excellent way to introduce metal cation vacancies in materials, thereby ensuing in highly enhanced catalytic performance. Inspired by this, we effectively constructed a built-in interface alpha-MnO2/Bi2WO6 heterostructure with abundant intimate interfaces and defective Mn3+/Mn4+ active sites for photocatalytic tetracycline hydrochloride (TC-HCl), hexavalent chromium Cr6+ reduction, and Escherichia coli (E. coli) inactivation. The experimental results, such as the active species test and X-ray photoelectron spectroscopy, indicated that the defective sites Mn3+/Mn4+, surface oxygen vacancies, and Bi(3+x)+ boosted the visible light absorption, and highly enhanced the photoinduced charge separation/transfer. Furthermore, experimental and DFT calculations reveal the high charge density at the built-in interface heterostructure and the Z-scheme charge transfer mechanism during the photocatalytic process. The results further reveal that O-2(-) and O-1(2) are the main reactive active species contributing to the photocatalytic reaction. The exceptional TC-HCl decomposition activity of the alpha-MnO2/Bi2WO6 heterostructure (97.56%, 2.31, and 2.04 times higher than bulk), enhanced reaction kinetics (K-app = 0.041 min(-1), 6.4, and 5.2 times higher than bulk), removal rate of 80.3%, Cr6+ reduction to Cr3+ (98.56%, K-app = 0.0599 min(-1)), and almost 100% bacterial inactivation compared to bulk alpha-MnO2 (42.22%) and Bi2WO6 (47.76%), were mainly due to the enhanced charge separation/transfer at the built-in interface and high charge density. This study opens new horizons for constructing Z-scheme MnO-based interface heterostructures with abundant defect sites for exceptional photocatalytic applications.

The catalytic efficiency of heterogeneous photocatalytic CO2 reduction and photo-Fenton H2O2 activation is closely related to the local electron density of reaction center atoms. However, electron-hole recombination from random charge transfer significantly restricts the targeted electron delivery to the active center. Herein, Fe C3N4/MoO3 heterojunction with interfacial coordination of atomically dispersed Fe-N4 sites with the O interface of MoO3 was synthesized by simple hydrothermal method. Based on the experimental results and density functional theory calculation (DFT), the heterojunction structure fosters accelerated interfacial electron transfer due to directional interfacial electric field (IEF) between Fe-CN and MoO heterogeneous interfaces, and the interfacial bond between Fe-N4 sites and O at the built-in interface regulates the local electron density of Fe-N4 active center. DFT further reveals that the interfacial electron flow and concentrated electron density at Fe-N4 sites result from the coordination between Fe-N4 and MoO3 interfaces. This directs electron flow towards the Fe center, significantly enhancing CO2 adsorption and H2O2 conversion efficiency. PDOS analysis shows that the d yz and d z 2 orbitals of the isolated Fe atom in Fe-CN overlap with the p z orbital of the O atom in MoO3, playing a pivotal role in CO2 adsorption. Consequently, the Fe-CN/MoO3 heterojunction demonstrated highly efficient photocatalytic CO2 reduction to CH4, coupled with benzyl alcohol oxidation and photo-Fenton tetracycline degradation. These findings offer a promising multifunctional catalyst strategy for the development of energy conversion and environmental remediation.

Biomimetic chiral optoelectronic materials can be utilized in electronic devices, biosensors and artificial enzymes. Herein, this work reports the chiro-optical properties and architectural arrangement of optoelectronic materials generated from self-assembly of initially nonchiral oligothiophene-porphyrin derivatives and random coil synthetic peptides. The photo-physical- and structural properties of the materials were assessed by absorption-, fluorescence- and circular dichroism spectroscopy, as well as dynamic light scattering, scanning electron microscopy and theoretical calculations. The materials display a three-dimensional ordered helical structure and optical activity that are observed due to an induced chirality of the optoelectronic element upon interaction with the peptide. Both these properties are influenced by the chemical composition of the oligothiophene-porphyrin derivative, as well as the peptide sequence. We foresee that our findings will aid in developing self-assembled optoelectronic materials with dynamic architectonical accuracies, as well as offer the possibility to generate the next generation of materials for a variety of bioelectronic applications.

This year at Communications Biology, we wanted to celebrate Transgender Day of Visibility by highlighting researchers at multiple career stages. In this Q&A, we asked early-career biologists about their own achievements, academic experiences, and how STEM can better support trans researchers.

In celebration of Pride Month, we asked transgender, genderqueer, and nonbinary scientists to tell us about what fascinates them, their ambitions and achievements, and how their gender identities have shaped their experiences in STEM. We owe a special thanks to 500 Queer Scientists (https://500queerscientists.com/), whose network and efforts at increasing LGBTQ+ scientists visibility made this article possible.

Plants are able to sense and respond to a myriad of external stimuli, using different signal transduction pathways, including electrical signaling. The ability to monitor plant responses is essential not only for fundamental plant science, but also to gain knowledge on how to interface plants with technology. Still, the field of plant electrophysiology remains rather unexplored when compared to its animal counterpart. Indeed, most studies continue to rely on invasive techniques or on bulky inorganic electrodes that oftentimes are not ideal for stable integration with plant tissues. On the other hand, few studies have proposed novel approaches to monitor plant signals, based on non-invasive conformable electrodes or even organic transistors. Organic electrochemical transistors (OECTs) are particularly promising for electrophysiology as they are inherently amplification devices, they operate at low voltages, can be miniaturized, and be fabricated in flexible and conformable substrates. Thus, in this study, we characterize OECTs as viable tools to measure plant electrical signals, comparing them to the performance of the current standard, Ag/AgCl electrodes. For that, we focused on two widely studied plant signals: the Venus flytrap (VFT) action potentials elicited by mechanical stimulation of its sensitive trigger hairs, and the wound response of Arabidopsis thaliana. We found that OECTs are able to record these signals without distortion and with the same resolution as Ag/AgCl electrodes and that they offer a major advantage in terms of signal noise, which allow them to be used in field conditions. This work establishes these organic bioelectronic devices as non-invasive tools to monitor plant signaling that can provide insight into plant processes in their natural environment.

Electrical signals in plants are mediators of long-distance signaling and correlate with plant movements and responses to stress. These signals are studied with single surface electrodes that cannot resolve signal propagation and integration, thus impeding their decoding and link to function. Here, we developed a conformable multielectrode array based on organic electronics for large-scale and high-resolution plant electrophysiology. We performed precise spatiotemporal mapping of the action potential (AP) in Venus flytrap and found that the AP actively propagates through the tissue with constant speed and without strong directionality. We also found that spontaneously generated APs can originate from unstimulated hairs and that they correlate with trap movement. Last, we demonstrate that the Venus flytrap circuitry can be activated by cells other than the sensory hairs. Our work reveals key properties of the AP and establishes the capacity of organic bioelectronics for resolving electrical signaling in plants contributing to the mechanistic understanding of long-distance responses in plants.

Body area networks (BANs), cloud computing, and machine learning are platforms that can potentially enable advanced healthcare outside the hospital. By applying distributed sensors and drug delivery devices on/in our body and connecting to such communication and decision-making technology, a system for remote diagnostics and therapy is achieved with additional autoregulation capabilities. Challenges with such autarchic on-body healthcare schemes relate to integrity and safety, and interfacing and transduction of electronic signals into biochemical signals, and vice versa. Here, we report a BAN, comprising flexible on-body organic bioelectronic sensors and actuators utilizing two parallel pathways for communication and decision-making. Data, recorded from strain sensors detecting body motion, are both securely transferred to the cloud for machine learning and improved decision-making, and sent through the body using a secure body-coupled communication protocol to auto-actuate delivery of neurotransmitters, all within seconds. We conclude that both highly stable and accurate sensing-from multiple sensors-are needed to enable robust decision making and limit the frequency of retraining. The holistic platform resembles the self-regulatory properties of the nervous system, i.e., the ability to sense, communicate, decide, and react accordingly, thus operating as a digital nervous system.

Smart agriculture tools as well as advanced studies on agrochemicals and plant biostimulants aim to improve crop productivity and more efficient use of resources without sacrificing sustainability. Recently, multiple advanced sensors for agricultural applications have been developed, however much less advancement is reported in the field of precise delivery of agriculture chemicals. The organic electronic ion pump (OEIP) enables electrophoretically-controlled delivery of ionic molecules in the plant tissue, however it needs external power-supplies complicating its application in the field. Here, we demonstrate that an OEIP can be powered by wind-driven leaf motion through contact electrification between a natural leaf and an artificial leaf. This plant-hybrid triboelectric nanogenerator (TENG) directly charges the OEIP, enabling proton delivery into a pH indicator solution, which triggers visible color changes as a proof-of-concept. The successful delivery of up to 44 nmol of protons was revealed by pH measurements after 17 h autonomous operation in air flow moving the plant and artificial leaves. Several control tests indicated that the proton delivery was powered uniquely by the charges generated during leaf fluttering. The OEIP-TENG combination opens the potential for targeted and self-powered long-term delivery of relevant chemicals in plants, with the possibility of enhancing growth and resistance to abiotic stressors.

The increasing energy demand and the ever more pressing need for clean technologies of energy conversion pose one of the most urgent and complicated issues of our age. Thermoelectricity, namely the direct conversion of waste heat into electricity, is a promising technique based on a long-standing physical phenomenon, which still has not fully developed its potential, mainly due to the low efficiency of the process. In order to improve the thermoelectric performance, a huge effort is being made by physicists, materials scientists and engineers, with the primary aims of better understanding the fundamental issues ruling the improvement of the thermoelectric figure of merit, and finally building the most efficient thermoelectric devices. In this Roadmap an overview is given about the most recent experimental and computational results obtained within the Italian research community on the optimization of composition and morphology of some thermoelectric materials, as well as on the design of thermoelectric and hybrid thermoelectric/photovoltaic devices.

Without intervention, cardiac arrhythmias pose a risk of fatality. However, timely intervention can be challenging in environments where transporting a large, heavy defibrillator is impractical, or emergency surgery to implant cardiac stimulation devices is not feasible. Here, we introduce an injectable cardiac stimulator, a syringe loaded with a nanoparticle solution comprising a conductive polymer and a monomer that, upon injection, forms a conductive structure around the heart for cardiac stimulation. Following treatment, the electrode is cleared from the body, eliminating the need for surgical extraction. The mixture adheres to the beating heart in vivo without disrupting its normal rhythm. The electrofunctionalized injectable cardiac stimulator demonstrates a tissue-compatible Young's modulus of 21 kPa and a high conductivity of 55 S/cm. The injected electrode facilitates electrocardiogram measurements, regulates heartbeat in vivo, and rectifies arrhythmia. Conductive functionality is maintained for five consecutive days, and no toxicity is observed at the organism, organ, or cellular levels. Heart pacing devices are bulky or rely on surgery. Here, the authors present an injectable cardiac stimulator based on a nanoparticle solution which attaches to the heart and forms a conductive path to the skin for external connection. It can regulate heartbeats and is thereafter cleared from the body.

Aim of present study was to synthesize a novel chitosan-quercetin (CTS-QT) complex by making a carbodiimide linkage using maleic anhydride as cross-linker and to investigate its enhanced antibacterial and antioxidant activities as compare to pure CTS and QT. Equimolar concentration of QT and maleic anhydride were used to react with 100 mg CTS to form CTS-QT complex. For this purpose, three bacterial strains namely E. Coli, S. Aureus and P. Aeruginosa were used for in-vitro antibacterial analysis (ZOI, MIC, MBC, checker board and time kill assay). Later molecular docking studies were performed on protein structure of E. Coli to assess binding affinity of pure QT and CTS-QT complex. MD simulations with accelerated settings were used to explore the protein-ligand complexs binding interactions and stability. Antioxidant profile was determined by performing DPPH center dot radical scavenging assay, total antioxidant capacity (TAC) and total reducing power (TRP) assays. Delivery mechanism to CTS-QT complex was improved by synthesizing polycaprolactone containing microspheres (CTS-QT-PCL-Levo-Ms) using Levofloxacin as model drug to enhance their antibacterial profile. Resulted microspheres were evaluated by particle size, charge, surface morphology, in-vitro drug release and hemolytic profile and are all were found within limits. Antibacterial assay revealed that CTS-QT-PCL-Levo-Ms showed more than two folds increased bactericidal activity against E. Coli and P. Aeruginosa, while 1.5 folds against S. Aureus. Green colored formation of phosphate molybdate complexes with highest 85 +/- 1.32% TAC confirmed its antioxidant properties. Furthermore, molecular docking and dynamics studies revealed that CTS-QT was embedded nicely within the active pocket of UPPS with binding energy greater than QT with RSMD value of below 1.5. Conclusively, use of maleic acid, in-vitro and in-silico antimicrobial studies confirm the emergence of CTS-QT complex containing microspheres as novel treatment strategy for all types of bacterial infections. Communicated by Ramaswamy H. Sarma